package com.lccviolet;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;

/**
 * @author LiChaochao
 * @Date 2021/9/9 11:53
 * @Description SpinLockDemo 实现一个自旋锁
 *
 * 好处：循环比较获取直到成功为之，没有类似wait的阻塞
 */
public class SpinLockDemo {

    // 原子引用线程
    AtomicReference<Thread> atomicReference = new AtomicReference<>();

    public void myLock() {
        Thread thread = Thread.currentThread();
        System.out.println(thread.getName() + " come in");

        while (!atomicReference.compareAndSet(null, thread)) {

        }
    }

    public void myUnlock() {
        Thread thread = Thread.currentThread();
        atomicReference.compareAndSet(thread, null);
        System.out.println(thread.getName() + " invoked myUnlock()");
    }

    public static void main(String[] args) {
        SpinLockDemo spinLockDemo = new SpinLockDemo();

        new Thread(() -> {
            spinLockDemo.myLock();
            try { TimeUnit.SECONDS.sleep(5); } catch (InterruptedException e) { e.printStackTrace(); }
            spinLockDemo.myUnlock();
        }, "AAA").start();

        try { TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }

        new Thread(() -> {
            spinLockDemo.myLock();
            try { TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }
            spinLockDemo.myUnlock();
        }, "BBB").start();
    }
}
